Which drug is not considered as primary antimycobacterial therapy?

Which drug is not considered as primary antimycobacterial therapy?

• A. Isoniazid
• B. Rifampin
• C. Pyrazinamide
• D. Kanamycin

Answer: (D)

Understanding first-line TB therapy is key here. In drug-susceptible tuberculosis, the initial standard regimen uses four drugs with strong bactericidal and sterilizing activity that are well tolerated and given orally: isoniazid, rifampin, pyrazinamide, and ethambutol. Kanamycin does not belong to this initial course. It is an injectable aminoglycoside reserved for second-line use, typically in multidrug-resistant TB or other resistant cases. Its role is limited by notable toxicities—especially ototoxicity (hearing loss) and nephrotoxicity—and the need for injections, which makes it unsuitable for routine first-line therapy. Therefore, kanamycin is not considered part of primary antimycobacterial therapy.

Understanding first-line TB therapy is key here. In drug-susceptible tuberculosis, the initial standard regimen uses four drugs with strong bactericidal and sterilizing activity that are well tolerated and given orally: isoniazid, rifampin, pyrazinamide, and ethambutol. Kanamycin does not belong to this initial course. It is an injectable aminoglycoside reserved for second-line use, typically in multidrug-resistant TB or other resistant cases. Its role is limited by notable toxicities—especially ototoxicity (hearing loss) and nephrotoxicity—and the need for injections, which makes it unsuitable for routine first-line therapy. Therefore, kanamycin is not considered part of primary antimycobacterial therapy.